Several such devices for delivering breathing gas to a patient are known in the art and widely used in the medical and therapeutical sectors. One important employment of the delivery of a breathing gas relates to treatment of sleep-related respiratory disorders, in particular of obstructive sleep apnea (OSA). Patients suffering from OSA are often supplied with a continuous positive airway pressure (CPAP) and/or a predetermined flow of a breathing gas during rest or sleep periods. This is achieved by the patient wearing a suitable breathing mask, which is connected to an apparatus, also referred to as blower, providing the necessary pressure and/or air flow. Due to the pressure being higher than ambient pressure the obstructed airways of the patient are “pushed” open, also referred to as pneumatic splinting, allowing for an adequate supply of breathing gas including oxygen.
In the art, there are known “closed” breathing masks which usually sealingly cover mouth and/or nose of a patient or user. Also known are “open” interfaces, such as a nasal cannula, which do not cover the mouth and/or nose of a patient but direct the breathing gas flow into the nose and/or mouth of a patient. Such cannula or “open” system is generally not sealed against the nose or mouth of a patient. Nasal cannulas are typically preferred by the user because they are more comfortable than “closed” masks, which usually are more bulky and have to be fixed to the user's head by a headband. Since these masks generally have to be applied over long periods, often during the whole night, there size and weight may turn out to influence the comfort of a patient.
However, such “open” interfaces and the systems known in the art applying such “open” interfaces have a number of disadvantages. These disadvantages particularly include the reduced operating conditions and the reduced application area vis-à-vis “closed” systems. In particular, it is problematic to adjust the applied therapy during therapy depending on the current patient conditions and particularly depending on the upper airway conditions of the user. This is particularly due to the “open” interface not being able to simultaneously perform therapy and diagnostic measures. It is also not possible to observe the severity of sleep disordered breathing during therapy. This would, however, be necessary to make sure that the necessary therapy is applied, e.g., that a patient is transferred to a standard CPAP therapy if he shows enhanced snoring or obstructive events.